When performing a wellbore operation such as a drilling operation, a tubular string may be introduced into the wellbore. Typically, the tubular string includes a plurality of tubular members and other downhole tools joined end-to-end by threaded joints to extend into the wellbore. Each joint typically includes a region of increased diameter of the tubular string. Additionally, other tools may include areas of increased diameter above the rest of the tubular string. As used herein, the term “tool joint” refers to a connection between joints of drillpipe, which may be, but is not necessarily, characterized by a transition or upset from the nominal tubular diameter.
In many operations, the tubular string passes through a rotating control device (RCD) and a blowout preventer (BOP) as the tubular string enters the wellbore. An RCD is a device that channels fluid returning through the annulus of the wellbore about the tubular string into a return line, while maintaining a fluid seal against the rotating and translating tubular string. Typically, at least one seal within the RCD contacts the outer surface of the tubular string and is at risk for damage if a change in diameter of the tubular string occurs too quickly.
A BOP is a control device that allows the wellbore or an annulus of the wellbore around the tubular string to be closed off at the wellhead such as, for example and without limitation, in the event of a blowout. The BOP may include one or more rams positioned to engage and seal against the outer surface of the tubular string and one or more rams positioned to shear the tubular string to seal off the wellbore. If such an operation occurs with a joint aligned with one or more of the BOP rams, the wellbore may not be fully sheared.
Because the BOP and RCD are positioned beneath the drill floor, an operator may have difficulty directly observing the tubular string to determine the relative location between tool joints and the BOP or RCD.
Typically, specifications of the components of the tubular string including the position of tool joints and other wellbore equipment on the tubular string are logged manually into a pipe tally database. Such a process is laborious and not always effective as tubulars are not always the same length due to recuts and special order lengths.